Determination of anaerobic ammonium oxidation (anammox) bacteria in the domestic wastewater

Wastewater treatment plants (WWTPs) in Malaysia are commonly associated with oxidation tank and activated sludge treatment processes. However, the removal rate of ammoniacal nitrogen from the wastewater still requires alternative technology as compared with the self-purification method. This provides a platform for further investigation of the degradation of nitrogen. Anaerobic ammonium oxidation (anammox) bacteria have been found to provide a shorter pathway for degradation of nitrogen in wastewater with limited presence of oxygen. The temperature, pH, dissolved oxygen (DO), total nitrogen, ammonia, nitrite and nitrate concentrations were analysed for the samples collected from the local WWTP. Influence of the various Malaysia weather conditions upon the treatment process was also observed. The temperature was found to fluctuate between 29.6°C and 32.0°C throughout the experiments at commemorating pH values of between 5.78 and 7.22 and DO concentration of 0.62–1.53 mg/L. Molecular analyses including genomic DNA (gDNA) extraction, polymerase chain reaction amplification and DNA sequencing were conducted to identify the presence of anammox bacteria. The gDNA of the sludge from anoxic and sequencing batch reactor tanks were successfully extracted with the gDNA amount of 24.40 and 31.67 µg, respectively. Anammox bacteria namely Kuenenia stuttgartiensis was found in the selected wastewater samples from the local WWTP. Thus, the presence of anammox bacteria enhances the removal of nitrogen from wastewater in a relatively quick and short process with further investigation regarding anammox bacterial growth and development.